4 Steps to Fix a Pool Heater That Won't Ignite

Check the gas supply first Confirm the shutoff valve at the heater and the main supply valve are open. For propane tanks, verify the tank isn’t empty. This is the most common fix.

Inspect the thermocouple or thermopile This small sensor near the pilot tells the gas valve to stay open. If dirty or failing, the heater will try to light and then shut off. Clean it gently with fine sandpaper or steel wool.

Replace a faulty thermocouple If cleaning doesn’t work, swap it out. They are cheap and easy to replace.

Check for a spark on electronic ignition models If you have an electronic ignition, listen for a spark when calling for heat. No spark points to a bad igniter or control board.